Systems and methods for feed-forward control of load current in dc to dc buck converters

ABSTRACT

A system for controlling load current in a voltage converter includes a current normalization module that receives a first measurement corresponding to the load current, receives a second measurement corresponding to an inductor current, and matches a first gain of the first measurement corresponding to the load current to a second gain of the second measurement corresponding to the inductor current to generate a normalized load current. A feed-forward generation module receives the normalized load current from the current normalization module and generates a load current feed-forward (LCFF) signal based on the normalized load current. A duty cycle generation module generates a duty cycle used to control the voltage converter based on a commanded output voltage of the voltage converter and the LCFF signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent Ser. No. 13/034,055,filed Feb. 24, 2011. The disclosure of the above application isincorporated herein by reference in its entirety.

FIELD

The present disclosure relates to control systems for power supplies andmore particularly to systems and methods for feed-forward control ofload current in direct current (DC) to DC buck converters.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

A power supply outputs a predetermined voltage that may be used to powerone or more components. For example, the predetermined voltage may powerone or more components of an integrated circuit (IC). In somesituations, however, a voltage that is less than the predeterminedvoltage may be sufficient to power one or more components. The lowervoltage may be obtained from the predetermined voltage using a voltagedivider circuit. Voltage divider circuits, however, are inefficient andinaccurate.

A step-down (i.e., buck) converter may be implemented to provide thelower voltage. Under certain conditions, a buck converter is generallymore efficient and more accurate than a voltage divider circuit. A buckconverter may include an inductor, a capacitor, two switches, and acontroller. The buck converter alternates between charging the inductorby connecting the inductor to the predetermined voltage and dischargingthe inductor to a load.

SUMMARY

A feed-forward control system for load current in a direct current (DC)to DC converter includes a current normalization module, a feed-forwardgeneration module, and a duty cycle generation module. The currentnormalization module generates a normalized load current by matching again of a measured load current to a gain of an inductor current. Thefeed-forward generation module that generates a load currentfeed-forward (LCFF) signal based on the normalized load current. Theduty cycle generation module generates a duty cycle for the DC to DCconverter based on a commanded output voltage and the LCFF signal.

A method for feed-forward control of load current in a direct current(DC) to DC converter includes generating a normalized load current bymatching a gain of a measured load current to a gain of an inductorcurrent, generating a load current feed-forward (LCFF) signal based onthe normalized load current, and generating a duty cycle for the DC toDC converter based on a commanded output voltage and the LCFF signal.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of a DC to DC buck converteraccording to one implementation of the present disclosure;

FIG. 2 is a functional block diagram of a control module for the DC toDC buck converter according to one implementation of the presentdisclosure;

FIG. 3A is a functional block diagram of a current normalization moduleand a feed-forward generation module according to one implementation ofthe present disclosure;

FIG. 3B is a flow diagram illustrating steps of a first method forfeed-forward control of load current in a DC to DC buck converteraccording to one implementation of the present disclosure;

FIG. 4A is a functional block diagram of the current normalizationmodule and the feed-forward generation module according to anotherimplementation of the present disclosure;

FIG. 4B is a flow diagram illustrating steps of a second method forfeed-forward control of load current in a DC to DC buck converteraccording to one implementation of the present disclosure;

FIG. 4C is a graph illustrating simulated results of the second methodfor feed-forward control of load current in a DC to DC buck converter;

FIG. 5A is a functional block diagram of a module for generating a loadcurrent feed-forward (LCFF) signal based on a product of a normalizedload current and a difference between inductor current and thenormalized load current, according to another implementation of thepresent disclosure;

FIG. 5B is a flow diagram illustrating steps of a third method forfeed-forward control of load current in a DC to DC buck converteraccording to one implementation of the present disclosure; and

FIG. 6 is a graph illustrating simulated results of implementingfeed-forward-control of load current in a DC to DC buck converteraccording to one implementation of the present disclosure while alsodecreasing feedback gains.

DETAILED DESCRIPTION

The following description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Forpurposes of clarity, the same reference numbers will be used in thedrawings to identify similar elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A or Bor C), using a non-exclusive logical or. It should be understood thatsteps within a method may be executed in different order withoutaltering the principles of the present disclosure.

As used herein, the term module may refer to, be part of, or include anApplication Specific Integrated Circuit (ASIC); an electronic circuit; acombinational logic circuit; a field programmable gate array (FPGA); aprocessor (shared, dedicated, or group) that executes code; othersuitable components that provide the described functionality; or acombination of some or all of the above, such as in a system-on-chip.The term module may include memory (shared, dedicated, or group) thatstores code executed by the processor.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared, as used above, means that some or allcode from multiple modules may be executed using a single (shared)processor. In addition, some or all code from multiple modules may bestored by a single (shared) memory. The term group, as used above, meansthat some or all code from a single module may be executed using a groupof processors. In addition, some or all code from a single module may bestored using a group of memories.

The apparatuses and methods described herein may be implemented by oneor more computer programs executed by one or more processors. Thecomputer programs include processor-executable instructions that arestored on a non-transitory tangible computer readable medium. Thecomputer programs may also include stored data. Non-limiting examples ofthe non-transitory tangible computer readable medium are nonvolatilememory, magnetic storage, and optical storage.

A voltage step refers to a change in the commanded output voltage of abuck converter. For example, a step-down refers to a decrease in thecommanded output voltage. A control system may control the outputvoltage by adjusting a duty cycle of switches in the buck converterbased on output voltage feedback. Slow feedback after a voltage step,however, may increase the response to a load step (“step response”) bythe control system. For example, the increased step response may cause adrop in output voltage. The bandwidth of the control system may beincreased to improve the step response. Increasing the bandwidth,however, may also increase noise.

“Apparent bandwidth” refers to an effective bandwidth achieved by thecontrol system. For example, the apparent bandwidth may be increasedwithout increasing the actual bandwidth of the control system.Therefore, increasing the apparent bandwidth of the control system mayimprove step response without increasing noise. Moreover, as a result ofthe increased apparent bandwidth, the size of the capacitor in the buckconverter may be decreased while maintaining a low voltage drop and asmooth recovery after a load step while also decreasing area and costs.Using feed-forward control of the load current may be used to increasethe apparent bandwidth of the control system.

Accordingly, systems and methods for feed-forward control of loadcurrent in a DC to DC buck converter are presented. For example, thesystems or methods may be implemented via (i) firmware/hardware, (ii)analog components (e.g., operational amplifiers), and/or (iii) digitalcomponents (e.g., a digital signal processing, or DSP controller). Thesystems and methods include generating a load current feed-forward(LCFF) signal based on the load current (and in some cases also based onthe inductor current). The LCFF signal may then be added to a base dutycycle (based on the commanded voltage) to generate the duty cycle forthe switches in the buck converter. For example, the load current may bemeasured using a printed circuit board (PCB) trace and the inductorcurrent may be measured using a direct-current resistance (DCR) method.

A resistance of a lead used to measure the load current, however, may beunknown and therefore the measured load current may be inaccurate.Therefore, the measured load current may be normalized to match a gainof the load current to a gain of the measured inductor current. Forexample, the normalized current may be generated using aleast-mean-square (LMS) filter. The LCFF signal may be generated basedon the normalized current according to one of three methods. A firstmethod includes generating the LCFF signal based on the normalizedcurrent. A second method includes generating the LCFF signal based on asquare of the error between the normalized current and the inductorcurrent. A third method includes generating the LCFF signal based on aproduct of the inductor current and a difference between the normalizedcurrent and the inductor current.

In some implementations, the first, second, or third methods may alsoimplement a high pass filter (HPF) to remove any DC error/offset. Forexample, DC offset may be present after an analog-to-digital (A-D)conversion. The systems and methods, however, apply to both digital andanalog systems. For example only, the systems and methods may decrease adrop in output voltage by 1.0-1.5%. Additionally, for example only, thesystems and methods may allow a size of the buck converter capacitor tobe decreased by 30-50% (thus decreasing area and costs) while stillmaintaining performance.

Referring now to FIG. 1, an example of a DC to DC buck converter 10 isshown. The buck converter 10 includes a switching module 12 thatcontrols a connection between an input voltage (V_(IN)) and an inductor14. Specifically, the switching module 12 switches the connectionbetween the inductor 14 and the input voltage V_(IN) according to a dutycycle. For example, the switching module 12 may include a digitalpulse-width modulator (DPWM) and field effect transistors (FETs) (notshown). A capacitor 16 is connected between the inductor 14 and groundto provide filtering of an output voltage (V_(OUT)) and smoothing of thestep response. When the switching module 12 disconnects the inputvoltage V_(IN) from the inductor 14, the inductor 14 and the capacitor16 (collectively referred to as an inductor-capacitor, or LC circuit)discharge at the output voltage V_(OUT) having a magnitude less than theinput voltage (V_(IN)).

A direct-current resistance (DCR) module 18 performs DCR current sensingto measure current flowing through the inductor (I_(IND)). For example,the DCR module 18 may include a resistor-capacitor (RC) circuit (notshown) connected in parallel across the inductor 14. A control module 20generates the duty cycle for the switching module 12 based on theinductor current I_(IND), load current (I_(LOAD)), and a commandedvoltage (V_(CMD)). The commanded voltage V_(CMD) represents a desiredvoltage to be generated by the buck converter 10.

The load current I_(LOAD), on the other hand, represents a currentflowing out of the buck converter 10 to a connected load. For example,the load current I_(LOAD) may be measured via a PCB trace. Morespecifically, the load current I_(LOAD) is measurable because an outputlead of the buck converter 10 has a built-in resistance. The built-inresistance, however, is unknown. Therefore, the measured load currentI_(LOAD) may be inaccurate. Accordingly, the measured load currentI_(LOAD) may be normalized by matching a gain of the measured loadcurrent I_(LOAD) to a gain of the inductor current I_(IND). For example,the measured load current may be normalized using an LMS filter (notshown).

Referring now to FIG. 2, an example of the control module 20 is shown.The control module 20 includes a current normalization module 50, afeed-forward generation module 54, a duty cycle generation module 58,and a main loop compensator module 62. The duty cycle generation module58 may further include a duty cycle module 66 and a summing module 70.

The current normalization module 50 receives the load current I_(LOAD)and the inductor current I_(IND). In some implementations, the currentnormalization module 50 may receive digital signals generated byanalog-to-digital (A-D) converters representing the load currentI_(LOAD) and the inductor current I_(IND), respectively. Alternatively,the current normalization module 50 may receive the load currentI_(LOAD) and the inductor current I_(IND) directly (i.e., analogoperation). The current normalization module 50 normalizes the loadcurrent I_(LOAD) to generate a normalized load current I_(N).Specifically, the current normalization module 50 matches a gain of theload current I_(LOAD) to a gain of the inductor current I_(IND).

The feed-forward generation module 54 receives the normalized loadcurrent I_(N). The feed-forward generation module 54 generates an LCFFsignal according to one of three methods (hereinafter referred to as thefirst, second, and third feed-forward methods, respectively). Accordingto the first feed-forward method, the feed-forward generation module 54may generate the LCFF signal based on the normalized load current I_(N).The LCFF signal generated by the first feed-forward method may representan inductor volt-second demanded by the load current.

According to the second feed-forward method, the feed-forward generationmodule 54 may generate the LCFF signal based on a square of the errorbetween the normalized load current I_(N) and the inductor currentI_(IND). The LCFF signal generated by the second feed-forward method mayrepresent an approximate duty cycle demanded by the load current.According to the third feed-forward method, the feed-forward generationmodule 54 may generate the LCFF signal based on a product of theinductor current I_(IND) and the difference between the normalized loadcurrent I_(N) and the inductor current I_(IND). The LCFF signalgenerated by the third feed-forward method may represent generate anideal duty cycle.

The main loop compensator module 62 generates a value for the duty cyclegeneration module 58. For example, the value may representfeedback-based control of the duty cycle. In other words, the value mayrepresent a required change in the duty cycle to achieve the commandedvoltage V_(CMD) at the output voltage V_(OUT). The duty cycle module 66generates a base duty cycle based on the value from the main loopcompensator module 62. The summing module 70 generates the duty cyclefor the switching module 12 based on a sum of the base duty cycle andthe LCFF signal (from the feed-forward generation module 54).

Referring now to FIG. 3A, an example of the current normalization module50 and the feed-forward generation module 54 according to the firstfeed-forward method is shown. The current normalization module 50includes a multiplier module 100, a sign module 102, a gain module 104,a summing module 106, a delay module 108, a multiplier module 110, andan error module 112.

The multiplier module 100 generates a product of the load currentI_(LOAD) and the normalized current I_(N) (received as feedback). Thesign module 102 switches a sign of the product. The gain module 104applies a gain to the signed product. The summing module 106 calculatesa sum of the output of the gain module 104 and a first correctionfactor. The delay module 108 introduces a one sample (Ts) delay to thesum to generate the first correction factor. For example, the one sampleTs delay may be introduced because a Laplace transformation convertedvarious metrics from the time domain to the frequency domain forpurposes of duty cycle control. The multiplier module 110 generates aproduct of the load current I_(LOAD) and the first correction factor.The error module 112 generates the normalized current I_(N) based on adifference between the inductor current I_(IND) and the product.

The feed-forward generation module 54 includes a gain module 120, anerror module 122, a saturation module 124, a summing module 126, a delaymodule 128, and an error module 130. The gain module 120 applies a gainto the normalized current I_(N). The error module 122 calculates anerror between the output of the gain module 120 and a second correctionfactor. The saturation module 124 limits the error to a predeterminedrange. For example, limiting the sum to a predetermined range (i.e.,saturation limits) may prevent windup. Additionally, for example only,the predetermined range may be based on a supply voltage (V_(DD)) and abulk voltage (V_(BULK)) of a low-side body diode. The summing module 126calculates a sum of the limited error and the second correction factor.The delay module 128 introduces a one sample Is delay to the output ofthe summing module 126 to generate the second correction factor. Theerror module 130 generates the LCFF signal based on a difference betweenthe sum and the second correction factor.

Referring now to FIG. 3B, the first feed-forward method begins at 150.At 150, the control module 20 measures the load current I_(LOAD) and theinductor current I_(IND). At 152, the control module 20 calculates aproduct of the load current I_(LOAD) and the normalized current I_(N).At 154, the control module 20 switches a sign of the product. At 156,the control module 20 applies a gain to the signed product. At 158, thecontrol module 20 calculates a sum of the modified product and a firstcorrection factor (CF₁). At 160, the control module 20 introduces a onesample Ts delay to the sum to generate the first correction factor CF₁.At 162, the control module 20 calculates a product of the load currentI_(LOAD) and the first correction factor CF₁. At 164, the control module20 generates the normalized current based on a difference between theproduct and the inductor current I_(IND). Control may then proceed to166. While one cycle is shown, in some implementations control mayreturn to 152 and repeat until the gain of the load current I_(LOAD) ismatched to the gain of the inductor current I_(IND).

At 166, the control module 20 applies a gain to the normalized currentI_(N). At 168, the control module 20 calculates an error between themodified current and a second correction factor (CF₂). At 170, thecontrol module 20 limits the error to a predetermined range (i.e.,saturation limits). At 172, the control module 20 calculates a sum ofthe limited error and the second correction factor CF₂. At 174, thecontrol module 20 introduces a one period Ts delay to the sum togenerate the second correction factor CF₂. At 176, the control module 20generates the LCFF signal based on a difference between the secondcorrection factor CF₂ and the sum. At 178, the control module 20generates the duty cycle for the switching module 12 based on a sum of abase duty cycle (based on the voltage command V_(CMD)) and the LCFFsignal. Control may then end.

Referring now to FIG. 4A, an example of the current normalization module50 and the feed-forward generation module 54 according to the secondfeed-forward method is shown. The current normalization module 50includes an error module 200, a gain module 202, a summing module 204, asaturation module 206, a delay module 208, and a multiplier module 210.

The error module 200 calculates a first error between the inductorcurrent I_(LOAD) and the normalized load current I_(N) (received asfeedback). The gain module 202 applies a gain to the first error. Thesumming module 204 calculates a sum of the output of the gain module 202and a first correction factor. The saturation module 206 limits the sumto a predetermined range. The delay module 208 introduces a one periodTs delay to the limited sum to generate the first correction factor. Themultiplier module 210 generates the normalized load current I_(N) basedon a product of the first correction factor and the load currentI_(LOAD).

The feed-forward generation module 54 includes a gain module 220, an HPFmodule 221, a squaring module 230, a gain module 232, an absolute valuemodule 234, and a switch module 236. The gain module 220 applies a gainto the first error calculated by error module 200.

The HPF module 221 includes an error module 222, a summing module 224, adelay module 226, an HPF gain module 228. The HPF module 221 sets acorner frequency for high-pass filtering to remove DC error/offset.Specifically, the error module 222 calculates a second error between theoutput of the gain module 220 and an output of the HPF gain module 228.The summing module 224 calculates a sum of the second error and a secondcorrection factor. The delay module 226 introduces a one period Ts delayto the sum to generate the second correction factor. The HPF gain module228 applies an HPF gain. As previously described, while the HPF module221 is implemented in the feed-forward generation module 54 according tothe second feed-forward method, the HPF module 221 (or a similar HPF)may also be implemented in the first and/or third feed-forward methodsfor removal of DC error/offset.

The squaring module 230 calculates a square of the second error. Forexample only, the squaring module 230 may calculate a product of thesecond error and an absolute value of the second error. The gain module232 applies a gain to the output of the squaring module 230. Theabsolute value module 234 calculates an absolute value of the output ofthe gain module 232. The switch module 236 generates the LCFF signal byselecting either the output of the gain module 232 or its absolute valueoutput by the absolute value module 234. For example only, the switchmodule 236 may select the output of the gain module 232 if the output ofthe gain module 232 is greater than a predetermined value and otherwisemay select the output of the absolute value module 234.

Referring now to FIG. 4B, the second feed-forward method begins at 250.At 250, the control module 20 measures the load current I_(LOAD) and theinductor current I_(IND). At 252, the control module 20 calculates afirst error between the inductor current I_(IND) and the normalizedcurrent I_(N). At 254, the control module 20 applies a gain to the firsterror. At 256, the control module 20 calculates a sum of the firstmodified error and a first correction factor (CF₁). At 258, the controlmodule 20 limits the sum to a predetermined range (i.e., saturationlimits). At 260, the control module 20 introduces a one period Ts delayto the limited sum to generate the first correction factor CF₁. At 262,the control module 20 generates the normalized current I_(N) based on aproduct of the first correction factor CF₁ and the load currentI_(LOAD). Control may then proceed to 264. While one cycle is shown,however, control may return to 252 and repeat until the gain of the loadcurrent I_(LOAD) is matched to the gain of the inductor current I_(IND).

At 264, the control module 20 applies a gain to the first error betweenthe inductor current I_(IND) and the normalized current I_(N) (see 252).At 266, the control module 20 calculates a second error between thesecond modified error and an HPF correction factor (CF_(HPF)). At 268,the control module 20 calculates a sum of the second error and a secondcorrection factor (CF₂). At 270, the control module 20 introduces a oneperiod Ts delay to the sum to generate the second correction factor CF₂.At 272, the control module 20 generates the HPF correction factorCF_(HPF) by applying an HPF gain to the second correction factor CF₂.

At 274, the control module 20 squares the second error. At 276, thecontrol module 20 applies a gain to the squared error. At 278, thecontrol module 20 calculates an absolute value of the product of thegain and the squared error. At 280, the control module 20 determineswhether the product is greater than a predetermined value. If true,control may proceed to 282. If false, control may proceed to 284. At282, the control module 20 may generate the LCFF signal based on theproduct and control may proceed to 286. At 284, the control module 20may generate the LCFF signal based on the absolute value of the productand control may proceed to 286. At 286, the control module 20 maygenerate the duty cycle for the switching module 12 based on a sum of abase duty cycle (based on the voltage command V_(CMD)) and the LCFFsignal. Control may then end.

Referring now to FIG. 4C, a graph illustrating simulated results of thesecond feed-forward method compared to conventional duty cycle controlis shown. As shown, feed-forward control of the load current I_(LOAD)improved response and decreased a droop in output voltage V_(OUT).Region 290 identifies the feed-forward control. Specifically, the LCFFsignal is added to the base duty cycle causing an increase in the dutycycle compared to the conventional duty cycle control. Region 292identifies the improved step response of the inductor current I_(IND).Specifically, the inductor current I_(IND) increases one PWM cycleearlier than the conventional duty cycle control. Lastly, region 294identifies the decreased drop in output voltage V_(OUT). Specifically,the drop in output voltage V_(OUT) is decreased by approximately1.0-1.5%.

Referring now to FIG. 5A, an example of a third LCFF module 74 accordingto the third feed-forward method is shown. The third LCFF module 74 maygenerate the LCFF signal based on a product of inductor current I_(IND)and a difference between the load current I_(LOAD) and the inductorcurrent I_(IND) (i.e., I_(IND)×[I_(LOAD)−I_(IND)]). The third LCFFmodule 74 may also perform current normalization according to thepresent disclosure. Specifically, the third LCFF module 74 may include amultiplier module 300, a sign module 302, a gain module 304, a summingmodule 306, a delay module 308, a multiplier module 310, an error module320, a multiplier module 322, and a gain module 324.

The multiplier module 300 calculates a product of the load currentI_(LOAD) and an error between the inductor current I_(IND) and thenormalized current I_(N) (received as feedback from the third LCFFmodule 74). The sign module 302 switches a sign of the product. The gainmodule 304 applies a gain to the signed product. The summing module 306calculates a sum of the output of the gain module 304 and a correctionfactor. The delay module 308 introduces a one sample Ts delay to the sumto generate the correction factor. The multiplier module 310 generatesthe normalized current I_(N) based on a product of the inductor currentI_(IND) and the correction factor. The error module 320 calculates theerror between the inductor current I_(IND) and the normalized currentI_(N). The multiplier module 322 calculates a product of the error andthe normalized current I_(N). The gain module 324 generates the LCFFsignal by applying a gain to the product.

Referring now to FIG. 5B, the third feed-forward method begins at 350.At 350, the control module 20 measures the load current I_(LOAD) and theinductor current I_(IND). At 352, the control module 20 calculates aproduct of the load current I_(LOAD) and an error between the inductorcurrent I_(IND) and the normalized current I_(N). At 354, the controlmodule 20 switches a sign of the product. At 356, the control module 20applies a gain to the signed product. At 358, the control module 20calculates a sum of the modified product and a correction factor (CF).At 360, the control module 20 introduces a one period Ts delay to thesum to generate the correction factor CF. At 362, the control module 20calculates a product of the inductor current I_(IND) and the correctionfactor CF. Control may then proceed to 364. While one cycle is shown,however, control may return to 352 and repeat until the gain of the loadcurrent I_(LOAD) is matched to the gain of the inductor current I_(IND).

At 364, the control module 20 calculates the error between the inductorcurrent I_(IND) and the normalized current I_(N) (see 352). At 366, thecontrol module 20 calculates a product of the error and the normalizedcurrent I_(N). At 368, the control module 20 generates the LCFF signalby applying a gain to the product. At 370, the control module 20generates the duty cycle for the switching module 12 based on a sum of abase duty cycle (based on the voltage command V_(CMD)) and the LCFFsignal. Control may then end.

Referring now to FIG. 6, a graph illustrating simulated results ofimplementing feed-forward control of load current in a DC to DC buckconverter while also decreasing feedback gains is shown. Specifically,the graph illustrates load current control with and without LCFFaccording to the present disclosure while decreasing feedback gainsapproximately 70%. As shown, the feed-forward control of load currentaccording to the present disclosure increases the robustness of thecontrol system. In other words, the curve identified as havingimplemented LCFF control has less output voltage error and an overallsmoother response. This graph, however, may be used merely forillustration of the robustness of the systems and methods of the presentdisclosure.

The broad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, the specification, and the following claims.

What is claimed is:
 1. A system for controlling load current in a voltage converter, the system comprising: a current normalization module that receives a first measurement corresponding to the load current, receives a second measurement corresponding to an inductor current, and matches a first gain of the first measurement corresponding to the load current to a second gain of the second measurement corresponding to the inductor current to generate a normalized load current; a feed-forward generation module that receives the normalized load current from the current normalization module and generates a load current feed-forward (LCFF) signal based on the normalized load current; and a duty cycle generation module that generates a duty cycle used to control the voltage converter based on a commanded output voltage of the voltage converter and the LCFF signal.
 2. The system of claim 1, wherein the current normalization module receives the first measurement via a printed circuit board trace.
 3. The system of claim 1, wherein the second measurement corresponds to a direct-current resistance measurement of the inductor current.
 4. The system of claim 1, wherein the LCFF signal corresponds to one of an inductor volt-second demanded by the load current, an approximate duty cycle demanded by the load current, and an ideal duty cycle.
 5. The system of claim 1, wherein, to generate the normalized load current, the current normalization module determines an error between (i) the second measurement corresponding to the inductor current and (ii) a corrected load current.
 6. The system of claim 1, wherein, to generate the normalized load current, the current normalization module determines a product of (i) the first measurement corresponding to the load current and (ii) a correction factor associated with the second measurement corresponding to the inductor current.
 7. The system of claim 1, wherein, to generate the normalized load current, the current normalization module determines a product of (i) the second measurement corresponding to the inductor current and (ii) a correction factor associated with the first measurement corresponding to the load current.
 8. The system of claim 1, wherein the feed-forward generation module generates the LCFF signal based on an error between the normalized load current and the second measurement corresponding to the inductor current.
 9. The system of claim 1, wherein the feed-forward generation module generates the LCFF signal based on a product of the second measurement corresponding to the inductor current, and a difference between the normalized load current and the second measurement corresponding to the inductor current.
 10. A method for controlling load current in a voltage converter, the method comprising: receiving a first measurement corresponding to the load current; receiving a second measurement corresponding to an inductor current; matching a first gain of the first measurement corresponding to the load current to a second gain of the second measurement corresponding to the inductor current to generate a normalized load current; generating a load current feed-forward (LCFF) signal based on the normalized load current; and generating a duty cycle used to control the voltage converter based on a commanded output voltage of the voltage converter and the LCFF signal.
 11. The method of claim 10, wherein receiving the first measurement includes receiving the first measurement via a printed circuit board trace.
 12. The method of claim 10, wherein the second measurement corresponds to a direct-current resistance measurement of the inductor current.
 13. The method of claim 10, wherein the LCFF signal corresponds to one of an inductor volt-second demanded by the load current, an approximate duty cycle demanded by the load current, and an ideal duty cycle.
 14. The method of claim 10, wherein generating the normalized load current includes determining an error between (i) the second measurement corresponding to the inductor current and (ii) a corrected load current.
 15. The method of claim 10, wherein generating the normalized load current includes determining a product of (i) the first measurement corresponding to the load current and (ii) a correction factor associated with the second measurement corresponding to the inductor current.
 16. The method of claim 10, wherein generating the normalized load current includes determining a product of (i) the second measurement corresponding to the inductor current and (ii) a correction factor associated with the first measurement corresponding to the load current.
 17. The method of claim 10, wherein generating the LCFF signal includes generating the LCFF signal based on an error between the normalized load current and the second measurement corresponding to the inductor current.
 18. The method of claim 10, wherein generating the LCFF signal includes generating the LCFF signal based on a product of the second measurement corresponding to the inductor current, and a difference between the normalized load current and the second measurement corresponding to the inductor current. 